Preheat your oven to 375°F (190°C). In a large bowl, toss the strawberries with granulated sugar and cornstarch until evenly coated. Transfer the mixture to a baking dish, spreading it out into an even layer.
In a separate bowl, combine oats, flour, brown sugar, and salt. Mix well to distribute the ingredients evenly.
Add the cold, cubed butter to the dry ingredients. Use your fingertips or a pastry cutter to work the butter into the mixture until it resembles coarse crumbs with some pea-sized pieces.
Sprinkle the crumble topping evenly over the strawberry filling in the baking dish.
Place the dish in the preheated oven and bake for about 40 minutes, or until the topping is golden brown and the filling is bubbling around the edges.
Remove the crumble from the oven and let it cool slightly before serving. The topping will be crisp, and the strawberries will be juicy and thickened from the cornstarch.
